/*
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * This software is open source.
 * See the bottom of this file for the licence.
 */

package org.dom4j.io;

import org.dom4j.Element;
import org.dom4j.ElementHandler;

/**
 * <p> <code>PruningElementStack</code> is a stack of {@link Element}instances
 * which will prune the tree when a path expression is reached. This is useful
 * for parsing very large documents where children of the root element can be
 * processed individually rather than keeping them all in memory at the same
 * time. </p>
 * 
 * @author <a href="mailto:james.strachan@metastuff.com">James Strachan </a>
 * @version $Revision: 1.2 $
 */
class PruningElementStack extends ElementStack
{
   /** ElementHandler to call when pruning occurs */
   private ElementHandler elementHandler;

   /**
    * the element name path which denotes the node to remove from its parent
    * when it is complete (i.e. when it is popped from the stack). The first
    * entry in the path will be a child of the root node
    */
   private String[] path;

   /**
    * The level at which a path match can occur. We match when we have popped
    * the selected node so the and the lastElementIndex points to its parent so
    * this value should be path.length - 2
    */
   private int matchingElementIndex;

   public PruningElementStack(String[] path, ElementHandler elementHandler)
   {
      this.path = path;
      this.elementHandler = elementHandler;
      checkPath();
   }

   public PruningElementStack(String[] path, ElementHandler elementHandler,
      int defaultCapacity)
   {
      super(defaultCapacity);
      this.path = path;
      this.elementHandler = elementHandler;
      checkPath();
   }

   public Element popElement()
   {
      Element answer = super.popElement();

      if((lastElementIndex == matchingElementIndex) && (lastElementIndex >= 0))
      {
         // we are popping the correct level in the tree
         // lets check if the path fits
         //
         // NOTE: this is an inefficient way of doing it - we could
         // maintain a history of which parts matched?
         if(validElement(answer, lastElementIndex + 1))
         {
            Element parent = null;

            for(int i = 0; i <= lastElementIndex; i++)
            {
               parent = stack[i];

               if(!validElement(parent, i))
               {
                  parent = null;

                  break;
               }
            }

            if(parent != null)
            {
               pathMatches(parent, answer);
            }
         }
      }

      return answer;
   }

   protected void pathMatches(Element parent, Element selectedNode)
   {
      elementHandler.onEnd(this);
      parent.remove(selectedNode);
   }

   protected boolean validElement(Element element, int index)
   {
      String requiredName = path[index];
      String name = element.getName();

      if(requiredName == name)
      {
         return true;
      }

      if((requiredName != null) && (name != null))
      {
         return requiredName.equals(name);
      }

      return false;
   }

   private void checkPath()
   {
      if(path.length < 2)
      {
         throw new RuntimeException("Invalid path of length: " + path.length
            + " it must be greater than 2");
      }

      matchingElementIndex = path.length - 2;
   }
}

/*
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided that the
 * following conditions are met:
 * 
 * 1. Redistributions of source code must retain copyright statements and
 * notices. Redistributions must also contain a copy of this document.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * 3. The name "DOM4J" must not be used to endorse or promote products derived
 * from this Software without prior written permission of MetaStuff, Ltd. For
 * written permission, please contact dom4j-info@metastuff.com.
 * 
 * 4. Products derived from this Software may not be called "DOM4J" nor may
 * "DOM4J" appear in their names without prior written permission of MetaStuff,
 * Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
 * 
 * 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org
 * 
 * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL METASTUFF, LTD. OR ITS CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 */
